The invention is directed at a device for absorbing electric noise. It has long been known that the electric noise on the line can be reduced with the aid of ferromagnetic material elements (U.S. Pat. No. 3,462,715).
Such a device is already known (EP-A-452992), in which two half-elements made from ferromagnetic material are housed in split casing, whose bases have elastic pretensioning means, which press the two magnetic elements onto one another.
The problem of the invention is to provide a simply constructed and reliably operating device for absorbing electric noise.
To solve this problem the invention proposes a device having the features of claim 1. Further developments of the invention form the object of the dependent claims, whose wording, like that of the abstract, is made by reference into part of the content of the description.
The device is used in such a way that the two elements made from the noise-preventing material and referred to hereinafter as ferrite elements, are inserted in the part shells of the casing and then the casing is placed around the electric cable. According to a further development of the invention the device for fixing the ferrite elements acts on at least one frontal corner edge of the ferrite element, which is perpendicular to the interface between the two ferrite elements. Thus, the fixing device engages in such a way that no forces arise which press the ferrite elements towards the interface, so that they cannot give way in the opposite direction.
According to a further development, the fixing device has a web engaging on the ferrite element and located in the vicinity of and sloping towards the corner of the casing half. During the manufacture of the casing, said web can be easily manufactured without additional costs.
The web can in particular have a notch in which comes to rest the corresponding corner of the ferrite element.
According to the invention, said web is shaped on the one hand on the end wall and on the other on the side wall of the casing. Between the two points where it is shaped, it is preferably free, so that it can apply a certain tension.
It is also possible for the web to be split, so that the mutually associated ends of the two parts of the web can engage on the ferrite element.
It can in particular be provided that the facing ends of the two web parts are bevelled and the bevel is in particular chosen in such a way that the sloping edges engage flat on the ferrite elements.
According to the invention, in the case of the two-part web, one web part is shaped on the end wall and the other on the side wall of the part shell of the casing.
According to the invention, the web or the two web parts do not extend up to the base of the part shells of the casing.
According to the invention, the device can have a locking device for locking the casing in the closed state. This ensures that the casing does not open again, so that the device remains effective. Advantageously, the locking device is so positioned and constructed that it does not project over the outside of the closed casing and is in particular entirely located within the casing. This excludes an intentional or unintentional access to the locking device.
The locking device can have a lug or tab shaped onto one edge of a casing half and which locks in a recess in the edge of the other casing half. As a result of this arrangement on the edge, it is possible to ensure that the lug or tab is no longer accessible when the casing is closed. The recess may only be open in the interior of the casing.
Locking can in particular be such that it takes place on the terminal edges of the recess.
According to a further development, the tab has a resilient locking tongue in the vicinity of at least one of its facing terminal ends.
According to the invention, the locking can be such that it opposes opening and this can e.g. be achieved through the nature of the spring positioning.
In order to, if necessary, open the locking device again, according to the invention the casing has an opening through which a special tool can be passed through to enable action to take place on the locking device. This enables a specialist to open and optionally replace the device.
The through opening for the cable can, according to the invention, be formed by two recesses in the end walls of the two casing halves. On closing the casing the two facing recesses then form the through opening. The two recesses can be displaced along the associated edges of the casing halves. This gives rise to constrictions, which can be used for compensating different cable diameters, without said recesses having to diverge from the smooth shape or form.
According to the invention, the through openings need not be circular and can e.g. be oval or elliptical.
The two part shells can e.g. be interconnected by a film hinge. However, it is also possible to manufacture them separately and interconnect them by plugging.